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3.4 Genetics, biodiversity & classification

  • Biological diversity – biodiversity – is reflected in the vast number of species of organisms, in the variation of individual characteristics within a single species and in the variation of cell types within a single multicellular organism.
  • Differences between species reflect genetic differences. Differences between individuals within a species could be the result of genetic factors, of environmental factors, or a combination of both.
  • A gene is a section of DNA located at a particular site on a DNA molecule, called its locus. The base sequence of each gene carries the coded genetic information that determines the sequence of amino acids during protein synthesis. The genetic code used is the same in all organisms, providing evidence for evolution.
  • Genetic diversity within a species can be caused by gene mutation, chromosome mutation or random factors associated with meiosis and fertilisation. This genetic diversity is acted upon by natural selection, resulting in species becoming better adapted to their environment.
  • Variation within a species can be measured using differences in the base sequence of DNA or in the amino acid sequence of proteins.
  • Biodiversity within a community can be measured using species richness and an index of diversity.

Source: AQA Spec

Included in this download

3.4.1DNA, genes and chromosomes
3.4.2DNA and protein synthesis
3.4.3Genetic diversity from mutation/meiosis
3.4.4Genetic diversity and adaptation
3.4.5Species and taxonomy
3.4.6Biodiversity within a community
3.4.7Investigating diversity